Electronic equipment uses semiconductor devices, such as, for example, memory devices. Memory devices may include random access memories (RAMs), flash memories (e.g., NAND flash device, NOR flash device), and other types of memories for storing data or information.
Memory systems on system boards are designed to incorporate higher density and faster operation due to the demands of applications that operate on the system boards. Two design techniques that may be employed to incorporate higher density of a memory system on a system board include using: serial connection configuration, such as, for example, cascading; and parallel interconnection configuration, such as, for example, multi-dropping. These design techniques may be used to overcome the density issue that determines the cost and operating efficiency of memory swapping between a hard disk and a memory system.
Various clocking methods can be used in such systems. Using a common source clock, the clock signal can become distorted due to the parallel nature of this arrangement. As well, it has several skew factors, has a limited operating frequency range when many devices are connected in a multi-drop fashion, and may not be used in high-speed applications. A source synchronous clocking system, using clock reshaping and retransmission, provides a higher frequency operating range and avoids some of the common synchronous clock skew factors, but introduces other skew factors that do not seriously affect the performance of the system.